Conventionally, after their manufacture, conjugated olefins such as aliphatic diolefins and vinyl aromatics often are inhibited with one or more materials to inhibit oxidation and to prevent spontaneous polymerization before it is desired e.g., during transport and storage. Most commonly tert-butyl catechol and hydroquinone are employed in amounts from about 10 to about 200 parts per million (ppm). Although these phenolic inhibitors are innocuous for many downstream process, their presence can complicate the production of high molecular weight materials such as plastics, elastomers, thermoplastic elastomers and the like. The inhibitors can cause excessive consumption of polymerization initiators and result in production of polymeric materials of too high or too low molecular weight, too wide or too narrow molecular weight distribution, unwanted gels and the like.
It has long been industrial practice to remove the phenolic inhibitors such as tert-butyl catechol by washing with caustic solutions, however, that can add unwanted moisture. Another technique is sorbing onto granular alumina, however, the capacity of the alumina is rather low and its sorbency for tert-butyl catechol is poorly regenerable. Accordingly, a simple efficient process to remove the phenolic inhibitor compounds, when their presence is no longer desired, is of great interest.
A sorbent material found to have unique properties is acidified active carbon prepared by contacting particulate active carbon with a highly acidic oxidizing medium. As described in Blytas U.S. Pat. Nos. 4,048,061 and Blytas 4,116,820 (both incorporated herein by reference) acidified active carbon has good utility in sorbing certain metal compounds from hydrocarbon liquids. Further, such acidified active carbons, after having their surface hydrogen ions exchanged by metal cations such as lithum, sodium, potassium and calcium, have been found efficient to remove water from gas streams as described by Mahajan et al, Separation Science and Technology, 17(8), pp 1019-1025 (1982).